In some cases, the best way to illustrate something happening on your screen is to show someone. Whether you want to train people on a particularly difficult program or show everyone how to fix a problem you've run into before, recording a screencast is an easy way to do it. Thankfully, there are plenty of applications that let you record your screen, save the video, and share it with friends.

Camtasia Studio is the most expensive screen recording tool in the roundup, but it's also one of the most feature packed. The last time we looked at the app it was Windows only, but the latest versions support Mac OS as well, and allow you to record your entire screen, single applications, or part of your display, save your screencasts in multiple formats, upload directly to YouTube, and more. You can quickly edit audio tracks separate from the video, so you can narrate what you've recorded later and then combine the tracks into a final video, and more.

CamStudio may be Windows only, but it's free, open-source, easy to use, and one of the most lightweight apps in the top five. You won't get as many features from CamStudio as you will from most of the others, but if you just want a quick way to record an occasional video, save it, and then work with it in another application that you prefer, CamStudio is perfect for the job. Still, there's as much love for CamStudio as there is hate for it, so your mileage may vary.

Jing is another TechSmith product, the same company behind Camtasia Studio. In addition to being a free and effective screenshot utility, it's also a free tool to take screencasts, and an affordable alternative to Camtasia Studio. Both the free and the pro versions only allow you to record five minute videos, and both of them allow you to upload video to Screencast.com and come with a free 2GB account for video sharing. They allow you to record all or part of your screen, and share your videos when complete. The free version only allows you to save videos in SWF format, while the pro version added MPEG-4 format. You'll have to shell out for the pro version if you want to upload videos directly to YouTube, record your webcam, or take screen recordings without the Jing branding on them.

Screenflow may be Mac-only, but it's one of the most feature-rich screencasting utilities in the roundup. You can record your entire or part of your display in HD, record from your monitor or a video camera, and record audio from your computer and your microphone simultaneously. You can also customize your cursors, add tiles and text to your video, and more. When you're finished recording your display, you can edit the audio and video streams independantly, decouple the audio and the video, add transitions to your video, annotate your video, export it in multiple formats, or upload directly to YouTube.

Screen recording webapp Screencast-o-Matic has come a long way since it was launched. The tool uses Java to record your screen and upload it to the web, so it works anywhere Java is supported. You can add captions to the video, share it, upload it to YouTube (in HD, even,) or save the video as an MP4, AVI, or flash video. Free accounts can do all of this, but pro accounts allow you to remove the Screencast-o-Matic watermark, password protect your screencasts, and download a Java app that lets you record screencasts offline. Pro accounts also get video editing tools.

Now that you've seen the top five, it's time to vote for an all out favorite.

Honorable mentions this week go to Apple's Quicktime X – in Max OS X 10.6 Snow Leopard and 10.7 Lion, you don't need a separate app to create screencasts. Lion can do it for you. Another honorable mention goes to Microsoft Expression Encoder, a feature-packed video production utility for Windows. It'll set you back $199, but for that price you can create live webcasts, screencasts, add watermarks, and publish it all for the Web in Silverlight.

Have something to say about one of the contenders? Want to make the case for your favorite? Sound off in the comments.